Leonardo Mattiello

Anodic oxidation of 9,9'-spirobifluorene in CH2Cl2 + 0.2 M Bu4NBF4. Electrochemical behaviour of the derived oxidation product

The physicochemical properties and electrochemical behaviour of products obtained by anodic oxidation of 2-aminofluorene in CH2Cl2 + 0.2 M Bu4NBF4 are presented together with the oxidation conditions.

Effects of polyphenol compounds on influenza A virus replication and definition of their mechanism of action.

A set of polyphenol compounds was synthesized and assayed for their ability in inhibiting influenza A virus replication. A sub-set of them showed low toxicity. The best compounds within this sub-set were 4 and 6g, which inhibited the viral replication in a dose-dependent manner. The antiviral activity of these molecules was demonstrated to be caused by their interference with intracellular pathways exploited for viral replication: (1) MAP kinases controlling nuclear-cytoplasmic traffic of viral ribonucleoprotein complex; (2) redox-sensitive pathways, involved in maturation of viral hemagglutinin protein.

Anodic behaviour of mono- and bisdithiafulvenyl-9,9′-spirobifluorene: insertion of vinylogous TTF into the spirobifluorenyle framework

Abstract New three-dimensional copolymers containing 9,9′-spirobifluorenyl-ethylene units were prepared by anodic oxidation of 9,9′-spirobifluorenes 2-mono- or 2,7′-disubstituted by a dithiafulvenyl unit. The synthesis, physicochemical properties and electrochemistry of both monomers and derived oligomers and polymers are reported.

Electrochemistry of 9,9′-spirobifluorene derivatives: 2-acetyl- and 2,2′-diacetyl-9,9′-spirobifluorene. Preparation of stereoisomeric 2,3-bis(9,9′-spirobifluoren-2-yl)butane-2,3-diols

2-Acetyl- and 2,2′-diacetyl-9,9′spirobifluorene 1 and 2 were studied by cyclic voltammetry in dimethylformamide. The corresponding anion radicals show remarkable persistency in aprotic DMF. The (apparent) standard potentials are E°=–1.77 V (SCE) and E°=–1.75 V for the (quasi-reversible) reduction of 1 and 2 to the anion radicals, respectively. Preparative electrolysis of 1 in DMF–Et4NClO4(0.1 mol dm–3), with excess acetic acid as proton donor, furnished alcohol 3 and the diastereoisomeric pinacols 5 and 6, which were isolated and characterized. The diastereoisomeric excess, de, as evaluated (NMR) on the electrolyzed solution was only slightly in favour of the (±) compound. Spectroscopic properties of compounds 1–6 are, inter alia, the 13C NMR chemical shift for the spiro-carbon at δ= 65.9 (TMS), and the fragmentation patterns in the mass spectra, with the 100% relative abundance of the molecular-ion M˙+ in the case of the aromatic ketones 1 and 2. Some comments on the influence of conformations of 5 and 6 and of the presence of an intramolecular hydrogen-bond in some intermediates and products are also presented.

DIRECT FORMYLATION OF 9,9′-SPIROBIFLUORENE: 2-CARBOXALDEHYDE-9,9′-SPIROBIFLUORENE AND 2,2′-DICARBOXALDEHYDE-9,9′-SPIROBIFLUORENE

The one-step formylations, using CH3OCHCl2/TiCl4 in CH2Cl2, of 9,9′-spirobifluorene to obtain 2-carboxaldehyde-9,9′-spirobifluorene and 2,2′-dicarboxaldehyde-9,9′-spirobifluorene in moderate to good yields are described. Previous works dealt with four-steps synthesis.

Electrochemistry of 9,9' spirobifluorene derivatives : electrosynthesis of stereoisomeric 2,3-bis(2'-acetyl-9,9'-spirobifluoren-2-yl)butane-2,3-diols and of 1-(2'-acetyl-9,9'-spirobifluoren-2-yl)ethanol and redox properties of polyacetylated spirobifluorenes

Abstract 2,2′-diacetyl-9,9′-spirobifluorene 3a, an axially dissymmetric compound, when dissolved in virtually aprotic solvent DMF, is characterised by several reduction peaks in the voltammetric experiments, using a glassy carbon electrode; the first two electron transfers are reversible, with standard potentials E10 = −1.75 V and E20 = −1.90 V vs sce (saturated calomel electrode) respectively. A third reduction step occurs with Ep = −2.40 V, at v = 50 mV −1 . The first two steps are pertinent to the formation of the anion radical A.− and of the dianion diradical −.A−. of 3a (A) respectively. Controlled potential electrolysis of 3a on a rvc electrode in DMF-Et4NClO4 (0.1 M), with acetic acid 1:1 mol 3a/mol acid added, furnishes the two diastereomeric keto-alcohols 4 and the six diastereomeric keto-pinacols 5–7. This result is obtained if the electrolysis is stopped after 1 F/mol 3a was passed. If the electrolysis is continued until both CO groups are reduced, a mixture of diastereomeric pinacols 8 is obtained. Spectroscopic properties of compounds 5–7 are sensitive to the various spatial arrangements in the isomers. Some aspects of the redox properties of 3a, as related to the spiro-structure of the molecule, are also discussed. Redox properties of tri- and tetra-acetylated spirobifluorenes 3b and 3c in virtually aprotic conditions, as determined through cyclic voltammetry, are in turn related to those of the diacetylated derivative 3a: compounds [3a, b, c] are the first examples of spirocompounds bearing multiple redox-active substituents.

Electronic excitations in solution-processed oligothiophene small-molecules for organic solar cells

First principles calculations based on density functional theory and many body perturbation theory have been employed to study the optical absorption properties of a newly synthesized oligo-thiophene molecule, with a quaterthiophene central unit, that has been designed for solution-processed bulk-heterojunction solar cells. To this aim we have employed the GW approach to obtain quasiparticle energies as a pre-requisite to solve the Bethe-Salpeter equation for the excitonic Hamiltonian. We show that the experimental absorption spectrum can be explained only by taking into account the inter-molecular transitions among the π-stacked poly-conjugated molecules that are typically obtained in solid-state organic samples.

Electrodeposition of polyfluorene on a carbon nanotube electrode

Electrophoretically deposited single-walled carbon nanotube (SWCNT) films on a transparent conducting surface are used as electrodes for the electrodeposition of a π-conjugated polymer formed by the oxidative coupling of fluorene units. This method provides a uniform coverage of the conducting surface with respect to SWCNTs chemically assembled on a gold substrate. Electron microscopy reveals the formation of a polymer–SWCNT nanostructure which imparts distinct electrical properties from those of the polymer electrodeposited on the neat electrode. By combining the attractive properties of SWCNTs and polyfluorene, these nanocomposites open up new opportunities to achieve electrical contacts in nano- to micro-devices.

Electrochemistry of some ethyl α-bromo(dihalophenyl) acetates and electrochemical synthesis of diastereoisomeric diethyl 2,3-bis (dihalogenophenyl) succinates

Ethyl α-bromo-2,4- or -3,4-dihalogenophenylacetates (ABr), where halogen = F or Cl, are prepared and electrolysed on reticulated vitreous carbon (RVC) in dimethylformamide containing Et4NClO4(0.1 mol dm–3). Potentiostatic reduction at E=–1.6 to –1.8 V versus SCE furnishes the corresponding racemic and meso succinates (AA)(13)–(16). Monoesters AH (5)–(8) are also isolated. An excess pf racemic isomer is observed for (14), (15), and (16). Voltammetric experiments show practically no difference between the reduction potentials of the isomeric compounds. Diastereoisomers can be distinguished by NMR spectroscopy, allowing diastereoisomeric excess (de) to be evaluated before isolation of the single products. A mechanism involving radical intermediates A˙ cannot be excluded. On this basis, the des can be explained by assuming different geometries for A˙ when the phenyl group bears different substituents.

Erbium doped organic compounds for integrated optics

In this paper, optical properties of novel 1.54 mum emitting organic compounds are presented. Erbium tris(8-hydroxyquinoline) and erbium dibromo-quinoline thin films have been solution processed and are compared by absorbance and infrared emission. Edges and flaws related to the processing of the two compounds are remarked.